This invention relates generally to sealed system refrigeration devices, and more particularly, to control systems for refrigerators.
Modern refrigerators typically include a compressor, an evaporator, and a condenser in a closed refrigeration circuit, and a number of fans that facilitate the refrigeration circuit and direct cooled air into refrigeration compartments. Conventionally, the compressor, evaporator and condenser are operated at a single speed, and a plurality of single speed fans are employed in association with the condenser, evaporator, condenser and also to direct cooled air throughout the refrigerator. Collectively, these components are sometimes referred to as a sealed system. While these single speed sealed systems have been satisfactory in the past, they are now perceived as disadvantageous in several aspects.
For example, such single speed systems often entail considerable temperature variation in operation of the refrigerator as the sealed system cycles on an off. Further, the refrigerator can sometimes be undesirably noisy as it cycles from an off or relatively silent condition to an on condition with the sealed system components energized. In addition, single speed systems are not as energy efficient as desired.
While most of these disadvantages can be addressed by using multiple speed or variable speed fans and sealed system components, use of variable speed components complicates the refrigeration controls considerably. A number of operating states corresponding to different combinations of the components at various speeds is virtually infinite, and finding and maintaining an optimal refrigerator state in an energy efficient manner can be formidable task. Additionally, manipulating component speeds in an energy efficient manner while responding to changing operating conditions and environments, such as door open events and ambient temperature fluctuation, is a challenge.
In one aspect, a method for controlling a sealed system including a variable speed compressor coupled to a controller is provided. The method comprises establishing a control grid having at least one axis corresponding to a temperature at a specified location, and the axis is divided into a plurality of operating states of the sealed system. Each of the states correspond to a sensed temperature condition at the specified location, and each of the states includes a designated compressor speed parameter. The compressor speed parameter in some of the states is different from the compressor speed parameter in other of the states.
In another aspect, a method for controlling a sealed system is provided. A controller is operatively coupled to a compressor operable at a multiplicity of speeds, a condenser fan operable at a multiplicity of speeds, and an evaporator fan operable at a multiplicity of speeds, and the controller is further coupled to at least a first thermistor in a first location. The method comprises sensing a temperature at the first location with the at least one thermistor, selecting optimum control parameters for the compressor, condenser fan and evaporator fan from one of a plurality of states corresponding to the sensed temperature in a control grid, and operating the compressor, condenser fan, and evaporator fan according to the control parameters.
In another aspect, a method for controlling a refrigeration system is provided. The refrigeration system includes a fresh food compartment and a freezer compartment with a damper establishing flow communication therebetween, and a sealed system for forcing cold air through the refrigerator compartments. The sealed system includes a compressor, a condenser fan, an evaporator fan and a fresh food compartment fan. The refrigerator further includes a controller operatively coupled to the compressor, the condenser fan, the damper, the evaporator fan and the fresh food fan. The method comprises reading data corresponding to a fresh food compartment condition, reading data corresponding to a freezer compartment condition, determining a state of the refrigeration system in a two-dimensional logic control grid based upon the fresh food compartment and the freezer compartment data, and executing an optimal control algorithm for the determined state of the refrigeration system. The optimal control algorithm includes one of a plurality of compressor speeds corresponding to the determined state.
In another aspect, a refrigeration device is provided. The refrigeration device comprises a compressor operable in a multiplicity of speeds, a controller operatively coupled to said compressor, and a thermistor coupled to said controller, said controller configured to adjust a speed of said compressor in response to a signal from said thermistor and a compressor speed parameter selected from a control grid containing a plurality of states of the refrigeration device.
In another aspect, a control system for a refrigeration system is provided. The refrigeration system includes a fresh food compartment and a freezer compartment with a damper establishing flow communication therebetween. A sealed system forces cold air through the refrigerator compartments, and the sealed system includes a compressor, a condenser, an evaporator fan and a fresh food compartment fan. The control system comprises a controller operatively coupled to the damper, the compressor, the condenser fan, the evaporator fan and the fresh food fan. The controller is configured to determine an applicable state of the refrigeration system in a two-dimensional logic control grid, execute an optimal control algorithm for the determined state of the refrigeration system, and adjust control parameters as the determined state changes over time, at least one of the parameters corresponding to a compressor speed.
In another aspect, a refrigerator is provided. The refrigerator comprises a cabinet, a first refrigeration compartment within said cabinet, a second refrigeration compartment within said cabinet, a damper establishing flow communication between said first and second refrigeration compartment, and a sealed system for forcing cold air through said first and second refrigerator compartments. The sealed system comprises a compressor, a condenser fan, an evaporator fan and a fresh food compartment fan and a controller is operatively coupled to said damper, said compressor, said condenser fan, said evaporator fan and said fresh food fan. The controller is configured to determine an applicable state of the refrigeration system in a two-dimensional logic control grid corresponding to temperature conditions of said first refrigeration compartment and said second refrigeration compartment, and adjust control parameters for said sealed system as said determined state changes over time, at least one of the parameters corresponding to a compressor speed value.